HOLYOKE — Mayor Alex B. Morse changed his mind and will listen to proposals for a casino gambling resort here because the reality is that the force of a giant gaming project in the region will affect Holyoke and it was best to try to influence that impact, he said Monday.

The first-term mayor spoke in a press conference at City Hall as protesters who were bitter that he is now welcoming casino gambling massed in the outer office and shouted that he was a liar and betrayed them.

Morse won many votes, especially in the Ward 7 area that could become home to a Mountain Park casino, from people glad he vowed opposition to a casino here.

"This was the beginning of a transparent process. People are assuming this is a done deal, and it's far from done. I am exploring the option, I set out guiding principles, and we will move forward," Morse said, asked later what it was like to hear people shout and see them hold signs that said he lied to and betrayed them.

A plan Morse said he could support is proposed by entertainment-venue owner Eric Suher, a Holyoke native, that would put a casino, hotel and convention center on the 70-acre Mountain Park music venue that Suher owns.

In other developments:

• Paper City Development, a limited liability company, said in light of Morse's turn-around it was back in the race to propose its own casino resort plan at Wyckoff Country Club on the Mount Tom Range.

• The City Council will form a five-councilor committee to review casino proposals.

• Mayors of Northampton and Easthampton said they were concerned a Holyoke casino would be detrimental to their communities.

The gaming law established a year ago permits three casinos in the state, including one in Western Massachusetts.

The deadline for companies to submit financial and other background material, as well as a nonrefundable fee of $400,000, to be considered by the Massachusetts Gaming Commission for a casino license is Jan. 15.

But the law gives the Gaming Commission discretion to give an extension to a company to file such information "in cases in which extraordinary circumstances prevented a timely filing."

The Gaming Commission Monday announced a process residents can use to comment on casino matters, with a link to its website.

"The Massachusetts Gaming Commission wants to know what you think," the commission said.

Morse's about-face comes with MGM Resorts International, Penn National Gaming and Ameristar Casinos battling to put a casino in Springfield and Mohegan Sun, of Uncasville, Conn., pitching a project for Palmer. Developers of those plans claim each would approach $1 billion.

"And the inescapable reality is that Holyoke cannot insulate itself from the economic realities of the surrounding region. A casino in downtown Springfield – especially one that reflects what has so far been proposed – would have a severe impact on our city," Morse said.

Morse said the series of events that began with him listening to Suher propose his plan in September signals only a willingness prompted by the economic realities of a casino in the region, not a done deal.

"Let me be absolutely clear. There is no agreement in place between a casino development group and me. There have been no back-room deal," he said.

Angry shouts from casino protesters forced Morse to try to talk over them as he read prepared remarks.

"You betrayed us," "You lied, Alex" and "Shame on you" were among the exclamations.

"We elected him with a promise that he was against a casino in Holyoke. That's why we elected him. And now he's betrayed that. He lied," said Russell Faille, of Lexington Avenue, holding a sign that read, "Morse Lied to Holyoke."

"He lied to us. He betrayed all of us," said Sharon Amos of Lyman Street.

Ward 7 voters outside Morse's office said they helped put him in office because he'd pledged not to put a casino in their backyards.

"I think what he did was unethical," said Ruth Epstein, of Harvard Street. "Voters in this city voted him in for a number of reasons, one of which was that there would be no casino."

"We feel very, very betrayed," said John Epstein, of Harvard Street.

Not all the comments directed at Morse were angry ones. Casino supporter Lorraine Gorham, of Joanne Drive, said as protesters shouted at the mayor that those like herself would work with Morse on getting Holyoke a casino.

"We have a large group of people, more than the protesters, and we're more than willing to work with you," Gorham said.

Suher's venue on the mountain has drawn major acts such as Bob Dylan and WIllie Nelson. The site used to be home to the Mountain Park Amusement Park, which closed in 1987. Suher owns the Iron Horse Music Hall, Pearl Street nightclub and the Calvin Theatre, all in Northampton.

But what makes Suher's plan agreeable, said Morse, saying he still doesn't like casinos – "In an ideal world, we would not have a casino within our boundaries" – is it would incorporate key features. It would make available to visitors of a casino resort here outdoor activities the mountain offers like hiking and canoeing and access to the Mount Tom State Reservation, he said.

Suher's plan also would require improvements be made downtown like extension of the CanalWalk, as part of the host-city agreement, he said.

Suher said Friday he is negotiating with Len and Mark Wolman, who are principals in the Waterford Group, of Waterford, Conn., to operate the casino at the resort he is proposing here.

Originally from South Africa, the Wolmans have been in partnerships on casinos such as the Mohegan Sun, a relationship that was said to have earned them more than $500 million, according to a 2005 report in the Hartford Courant. The Wolmans also have stakes in hotels and are major figures in the Connecticut development scene.

Another figure was a Connecticut tie is involved here now. David B. Panagore, who was deputy director of the Springfield Finance Control Board and most recently chief operating officer in Hartford, will be the city's development consultant on the casino project. He will be paid with fees provided by whichever operator manages the resort's casino, Morse said.

Paper City Development consists of manager Joseph A. Lashinger Jr., who has held gaming licenses in Pennsylvania, Mississippi, Colorado, Louisiana, West Virginia and Ontario, Canada; Anthony L. Cignoli, of the A.L. Cignoli Co. public relations firm, of Springfield, and former Springfield City Councilor Anthony Ravosa Jr., who now lives in Connecticut.

Cignoli and Ravosa said they are in talks with casino operators for their venture. Paper CIty Development had been working with Hard Rock International to run the casino last year. It was unclear who the casino operator would be now, they said, but the frenetic interest in Holyoke as a casino site of the past few days seems to ensure a casino partner won't be a problem.

Holyoke CIty Council President Kevin A. Jourdain and Ward 6 Councilor Todd A. McGee have filed an order to establish a Special Committee on a Holyoke Casino. The committee will analyze proposals, take testimony and ensure the process is open to the public, Jourdain said.

Morse's failure to be open about his casino plans, such as meeting with Suher without other officials' knowledge, means such a committee is necessary to protect the public, Jourdain said.

The mayor's credibility has suffered because of the way he has handled the casino issue, he said.

"As you know, he's already been on shaky ground with us for the first 11 months of his administration. You're only as good as your word," Jourdain said.

"When you take a stand you better stand by that stand, unless new information comes up and it makes sense for you to change that stand. Has that happened in this case? I don't know. The mayor hasn't been transparent," he said.

Morse replied, "I look forward to having a conversation with Councilor Jourdain and other City Councilors in the coming days and weeks about this issue."

Northampton Mayor David Narkewicz and Easthampton Mayor Michael A. Tautznik said in separate statements that Morse's casino change surprised them and they were eager to speak to him about details.

Narkewicz said his position is unchanged, that a nearby casino would be a "serious potential threat to the social and economic vitality of Northampton ..."

"I have serious concerns about a resort casino located six miles from the heart of downtown Northampton and will work with other surrounding communities to protect our interests and the interests of the region should any casino proposal be advanced in Holyoke," Narkewicz said.

Tautznik said he is concerned about about a Holyoke casino's traffic further congesting the already busy Route 141 between Easthampton and Holyoke.

It was an unusual press conference, beyond just the anti-Morse sloganeering while he read his remarks. Former Mayor Elaine A. Pluta, whom Morse defeated slightly more than a year ago, stood behind the desk she once occupied as Morse took questions.

"I'm excited," Pluta said. "It just vindicates my position on the issue. I think that Holyoke has the best location."

Pluta told Morse during the question-and-answer period that he was wrong in saying the Paper City Development plan would be just a box casino putting traffic into a residential area.

Also, Pluta told Morse, the Mountain Park area could be problematic for a casino because ledgy terrain.

"I appreciate the feedback," Morse said.

Police Chief James M. Neiswanger, who was among the array of department heads standing behind Morse during the press conference, said he supported putting a casino here.

"I think it's business, it's jobs and it's taxes, and I'm for any business that brings jobs and tax revenue to the city.

"The city is approaching its tax levy ceiling, and when we hit that, it's going to be tougher to deliver city services," he said.

Worries about a casino increasing crime are overblown, he said. Such large developments usually invest in high-technology surveillance and other security steps, he said.

"They want to protect their customers," Neiswanger said.

Also supportive of Morse's position was Kathleen G. Anderson, president of the Greater Holyoke Chamber of Commerce.

"I do share the mayor's sentiments that I am not a casino person, but I do like development," Anderson said.

Morse's switch from opposition to welcoming a casino cost him at least two supporters on city boards.

Jennifer Boyle, a Pleasant Street resident and the presumptive incoming chairwoman of the Holyoke Cultural Council, said she would resign her Jan. 1.

"Additionally, the hours I was able to spend proactively working for the city will now have to be spent reactively, in comprehensive and unrelenting opposition to a casino being sited in Ward 7," Boyle wrote to the mayor.

Daphne Board, a Suffolk Street resident said that as of Jan. 1 she will resign from the Cultural Council, Holyoke Redevelopment Authority Citizen Participation Committee and the Cable Access Advisory Group.